Merge branch 'matrix-org-hotfixes' of github.com:matrix-org/synapse into matrix-org-hotfixes

1 files changed, 14 insertions, 2 deletions

diff --git a/synapse/events/utils.py b/synapse/events/utils.py

index 7ca5c9940a..0f8a3b5ad8 100644
--- a/synapse/events/utils.py
+++ b/synapse/events/utils.py
@@ -22,6 +22,7 @@ from synapse.api.constants import EventTypes, RelationTypes
 from synapse.api.errors import Codes, SynapseError
 from synapse.api.room_versions import RoomVersion
 from synapse.util.async_helpers import yieldable_gather_results
+from synapse.util.frozenutils import unfreeze
 
 from . import EventBase
 
@@ -54,6 +55,8 @@ def prune_event(event: EventBase) -> EventBase:
         event.internal_metadata.stream_ordering
     )
 
+    pruned_event.internal_metadata.outlier = event.internal_metadata.outlier
+
     # Mark the event as redacted
     pruned_event.internal_metadata.redacted = True
 
@@ -400,10 +403,19 @@ class EventClientSerializer:
                 # If there is an edit replace the content, preserving existing
                 # relations.
 
+                # Ensure we take copies of the edit content, otherwise we risk modifying
+                # the original event.
+                edit_content = edit.content.copy()
+
+                # Unfreeze the event content if necessary, so that we may modify it below
+                edit_content = unfreeze(edit_content)
+                serialized_event["content"] = edit_content.get("m.new_content", {})
+
+                # Check for existing relations
                 relations = event.content.get("m.relates_to")
-                serialized_event["content"] = edit.content.get("m.new_content", {})
                 if relations:
-                    serialized_event["content"]["m.relates_to"] = relations
+                    # Keep the relations, ensuring we use a dict copy of the original
+                    serialized_event["content"]["m.relates_to"] = relations.copy()
                 else:
                     serialized_event["content"].pop("m.relates_to", None)